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January 16, 2014

Flying Jellyfish Drone Takes Flight

by redOrbit Staff & Wire Reports - Your Universe Online

redOrbit Staff & Wire Reports - Your Universe Online

Scientists at New York University announced Wednesday that they have built a prototype of the world’s first jellyfish drone. The tiny, electrically powered machine weighs in at just 2.1 grams and can hover in a stable manner without the use of sensors, recover from disturbances and maneuver in ways resembling a flying jellyfish, the researchers said.

Previous designs for so-called flapping wing aircraft, or ornithopters, have primarily imitated the wing motions of insects, but the latest design shows the value of researching flying strategies not yet explored by evolution, the researchers said.

"We were interested first of all in making a robotic insect that would be an alternative to the helicopter," said Dr. Ristroph, who works alongside Childress in applied mathematics at NYU’s Courant Institute. “Our interest ended up being a little bit weird - it was the jellyfish,” he told Agence France-Press (AFP).

The team didn’t originally set out to model insects, birds, or even jellyfish, but began instead with mathematics, seeking to find the “simplest scheme that should generate upwards force,” Dr. Ristroph explained in an interview with The New York Times.

The researchers began with “force diagrams in our heads,” he said. But pure calculations were not enough.

“The aerodynamics involved in flapping wing flight are so complicated that we can’t just make predictions,” Ristroph said, explaining the need for physical models.

The scientists calculated that pyramids and cones were the best shapes to begin modeling, and then floated objects of these shapes in puffs of air to see how they behaved. Based on the results, they constructed a machine with four flapping, petal-shaped wings, each four inches long, which when folded together formed a downward-facing cone.

A tiny motor attached to a crankshaft causes the wings to push outwards and then downwards 20 times per second, forcing out air through the bottom of the cone.

It was only later that the team realized their ornithopter was mimicking a jellyfish, Dr. Ristroph said.

The team published one mathematical model describing how the flapping wings reorganize airflow to keep the ornithopter upright, although Ristroph said he is not entirely satisfied with the model.

“We are presenting this problem to the wider scientific community,” he said.

Dr. Ristroph said he doesn’t know if a “jellyfishlike flying machine” would ever find a practical use. “If it’s going to be useful, we’ll need to get engineers excited about it,” he said.

In the meantime, a lot of work is needed on maneuverability and energy efficiency, but perhaps someday flapping unmanned aircraft could be a common sight, he told AFP.

"There's definitely some military use for things like this, such as in surveillance, but I hope that it has a civilian outlet too. I can imagine a cluster of a hundred of these being thrown out and fanning out across in a city to monitor air pollution."

When asked if the tiny aircraft prototype has an official name, Ristroph said he and Childress refer to their prototype as “our flying jellyfish.”